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1.
Mayfly emergence was studied in the Plitvice Lakes National Park (Croatia) monthly over a 2-year period in four habitats (springs, streams, mountainous rivers, tufa barriers) using monthly collections of emergence traps. A total of 12 mayfly taxa were recorded. Almost half of the collected specimens belonged to the genus Baetis Leach, 1815, which was recorded at every site, but we were unable to distinguish between two included species (B. rhodani and B. cf. nubecularis). Other abundant species were Centroptilum luteolum (Müller, 1776), Alainites muticus (Linnaeus, 1758), Habrophlebia lauta Eaton 1884, Paraleptophlebia submarginata (Stephens, 1835), Serratella ignita (Poda, 1761), Ephemera danica Müller, 1764 and Rhithrogena braaschi Jacob, 1974. The mayfly assemblages at all sites were dominated by species typical of the rhithral zone, but there was a shift in species composition along a longitudinal gradient (from 720 to 390 m a.s.l.) from dominance of eucrenal–epirhithral to metarhithral–hyporhithral elements and finally to appearance of metapotamal and littoral elements. Two environmental factors, maximum water temperature and mean pH, had the highest influence on the mayfly assemblages. Emergence mainly occurred between March and November and was related to the elevated water temperature. Emergence patterns of some species were in accordance with their typical Central European emergence patterns (e.g. S. ignita, H. lauta) while some others showed certain discrepancies (e.g. longer emergence period in Rh. braaschi and P. submarginata, one generation emergence in A. muticus and variable emergence patterns between the sites and between the two studied years in C. luteolum). The current study provides a significant contribution to the knowledge of mayfly ecology in karst freshwater habitats which forms a basis for further investigation and monitoring of mayflies in this area.  相似文献   

2.
Central European wet meadows are diminished by abandonment of cultivation measures, drainage, pollution, intensive agriculture and climate change during the last decades. In addition, original wet meadow communities can be threatened by immigrating neophytes. Typical invasive species in wet meadows are the steeplebushes Spiraea tomentosa and Spiraea douglasii, but their impact on the indigenous arthropod fauna is unknown. The present study therefore investigates Spiraea-induced changes in ground- and herb dwelling spiders in Spiraea sites, uncultivated meadows with interspersed Spiraea sp. and mowed meadows without Spiraea sp. using pitfall traps and sweep netting. Light intensity, vegetation height and coverage differed significantly between the Spiraea sites and the mowed meadows. In consequence, the activity density of ground-dwelling spiders was much lower in the Spiraea sites and their habitat preferences differed significantly from the two meadow types. Species preferring forests and forest edges were more abundant in invaded sites whereas specimens preferring open habitats decreased. Although the vegetation height and coverage of mowed meadows and cultivated meadows did not differ remarkably, uncultivated meadows contained less spiders of open dry habitats whereas forest species increased. In contrast, differences between herb dwelling spider assemblages of the three habitat types were not significant. Based on the results of the project, the risk of steeple bush invasion and management methods of wet meadows are discussed.  相似文献   

3.
Results of investigation of the species composition and population density of the orthopteran assemblages, performed in the Hissar Valley in 1935 and 1989 are discussed. The increased anthropogenic press resulted in the drastic changes in the assemblages during 50 years. Two species dominating in the past, Calliptamus italicus (L.) and Dociostaurus maroccanus (Thunb.), are indicators of the integrity of original assemblages (and entire ecosystems of Hissar Valley, which are now completely destroyed) or of their insignificant transformation. The recent mesomorphic assemblages are dominated by Oxya fuscovittata (Marsch.), Duroniella gracilis Uv., Chorthippus biguttulus (L.), Aiolopus thalassinus (Fabr.), and xeromorphic communities, by Calliptamus barbarus (Costa), Dociostaurus tartarus (Stshelk.), Oedipoda miniata (Pall.), and Acrotylus insubricus (Scop.). The predominance and wide distribution of these species points to a significant transformation of ecosystems and destabilization of the environment in the Hissar Valley.  相似文献   

4.
Amphibian populations are decreasing worldwide due to a variety of factors. In South America, the chytrid fungus Batrachochytrium dendrobatidis (Bd) is linked to many population declines. The pathogenic effect of Bd on amphibians can be inhibited by specific bacteria present on host skin. This symbiotic association allows some amphibians to resist the development of the disease chytridiomycosis. Here, we aimed (1) to determine for the first time if specific anti-Bd bacteria are present on amphibians in the Andes of Ecuador, (2) to monitor anti-Bd bacteria across developmental stages in a focal amphibian, the Andean marsupial tree frog, Gastrotheca riobambae, that deposits larvae in aquatic habitats, and (3) to compare the Bd presence associated with host assemblages including 10 species at sites ranging in biogeography from Amazonian rainforest (450 masl) to Andes montane rainforest (3200 masl). We sampled and identified skin-associated bacteria of frogs in the field using swabs and a novel methodology of aerobic counting plates, and a combination of morphological, biochemical, and molecular identification techniques. The following anti-Bd bacteria were identified and found to be shared among several hosts at high-elevation sites where Bd was present at a prevalence of 32.5%: Janthinobacterium lividum, Pseudomonas fluorescens, and Serratia sp. Bd were detected in Gastrotheca spp. and not detected in the lowlands (sites below 1000 masl). In G. riobambae, recognized Bd-resistant bacteria start to be present at the metamorphic stage. Overall bacterial abundance was significantly higher post-metamorphosis and on species sampled at lower elevations. Further metagenomic studies are needed to evaluate the roles of host identity, life-history stage, and biogeography of the microbiota and their function in disease resistance.  相似文献   

5.
Fourteen species of echinoderms and their relationships to the benthic structure of the coral reefs were assessed at 27 sites—with different levels of human disturbances—along the coast of the Mexican Central Pacific. Diadema mexicanum and Phataria unifascialis were the most abundant species. The spatial variation of the echinoderm assemblages showed that D. mexicanum, Eucidaris thouarsii, P. unifascialis, Centrostephanus coronatus, Toxopneustes roseus, Holothuria fuscocinerea, Cucumaria flamma, and Echinometra vanbrunti accounted for the dissimilarities among the sites. The spatial variation among the sites was mainly explained by the cover of the hard corals (Porites, Pocillopora, Pavona, Psammocora), different macroalgae species (turf, encrusting calcareous algae, articulated calcareous algae, fleshy macroalgae), sponges, bryozoans, rocky, coral rubble, sand, soft corals (hydrocorals and octocorals), Tubastrea coccinea coral, Balanus spp., and water depth. The coverage of Porites, Pavona, and Pocillopora corals, soft coral, rock, and Balanos shows a positive relationship with the sampling sites included within the natural protected area with low human disturbances. Contrary, fleshy macroalgae, sponges, and soft coral show a positive relationship with higher disturbance sites. The results presented here show the importance of protecting the structural heterogeneity of coral reef habitats because it is a significant factor for the distribution of echinoderm species and can contribute to the design of conservation programs for the coral reef ecosystem.  相似文献   

6.
Gravel-sand river terraces were nearly eliminated from central European landscape by river channelization. Monotypic stands of common reed (Phragmites australis) growing on such terraces are often stressed by drought, which makes them vulnerable to Lipara spp. (Diptera: Chloropidae) gallmakers. Although Lipara are considered ecosystem engineers, only fragmentary information is available on the biology of their parasitoids and inquilines. We analyzed the assemblages of arthropods (Arachnida, Collembola, Dermaptera, Psocoptera, Thysanoptera, Hemiptera, Raphidioptera, Neuroptera, Coleoptera, Diptera, Lepidoptera and Hymenoptera) that emerged from 17,791 Lipara-induced galls collected in winter from 30 reed beds in the Czech Republic, 15 of which were situated at (post)industrial sites (gravel-sandpits, tailing ponds, limestone quarries, colliery dumps, and reclaimed lignite open-cast mines) and 15 were in near-natural habitats (medieval fishponds, and river and stream floodplains). The Chao-1 estimator indicated 229.3 ± 18.1 species in reed galls at (post)industrial and 218.1 ± 23.6 species at near-natural sites, with the Sørensen index reaching only 0.58. We identified 18 red-listed species and four new species for the Czech Republic (Gasteruption phragmiticola, Echthrodelphax fairchildii, Haplogonatopus oratorius and Enclisis sp.), representing mostly obligate (64 %) or facultative (9 %) reed specialists. We propose that Lipara gall-associated assemblages undergo a long-term cyclic ecological succession. During first 10 years after reed bed formation, only Lipara spp. and several other species occur. During next decades, the reed beds host species-rich assemblages with numerous pioneer species (Singa nitidula, Polemochartus melas) that critically depend on presence of prior disturbances. Middle-aged reed beds (near medieval fishponds) are prevalently enriched in common species only (Oulema duftschmidi, Dimorphopterus spinolae). Habitats with the longest historical continuity (river floodplains) host again species-rich assemblages with several rare species that probably require long-term habitat continuity (Homalura tarsata, Hylaeus moricei). Landscape dynamics is thus critical for the persistence of a full spectrum of reed gall inquilines, with (post)industrials serving as the only refugia for pioneer species ousted from their key nesting habitats at once cyclically disturbed gravel-sand river terraces.  相似文献   

7.
Chironomid larvae assemblages were investigated at seven sampling stations in relation to stream habitat type in the Challhuaco-Ñireco river system located in the Nahuel Huapi National Park, in the North-Western part of Rio Negro Province, Argentina. A total of 2229 individuals were sampled and 43 Chironomidae taxa were recorded with Orthocladiinae (29) being the best represented subfamily, followed by Diamesinae (5), Tanypodinae (3), Podonominae (3) and Chironominae (3). Stictocladius spF, Cricotopus (Paratrichocladius) sp6, Cricotopus sp2, Cricotopus sp3 and Parapsectrocladius sp2 were the most abundant taxa. Sites near the source of the river system were dominated by Podonomus sp., Limnophyes sp., Parapsectrocladius sp. and Stictocladius spF, whereas sites close to the river mouth were dominated by Diamesinae sp5 and Cricotopus sp. Rank/abundance plots show that all the analysed sites displayed dominance of some species. Stictocladius spF, Cricotopus sp2, Cricotopus sp3, Cricotopus (Paratrichocladius) sp6, Parapsectrocladius sp. and Limnophyes sp. resulted as dominant species, or being part of a group of dominant species, at least in one sample. Eleven taxa were associated with habitats related with riffle areas and stable substrates with filamentous algae. Species–environment relationships were examined using ordination analysis. Elevation was the most significant environmental variable that explained 22% of the total variability of the chironomid assemblages, showing stronger relationships among sites within an altitudinal gradient than among habitat type. Abundance of chironomids increased from headwaters to the outflow in Nahuel Huapi Lake responding to an altitude gradient as well as some environmental factors such as coarse matter and nutrient concentrations.  相似文献   

8.
The diatom assemblages of the surface sediments have been studied in 53 urban ponds and lakes of St. Petersburg for the first time. In total, 350 species and infraspecific taxa have been registered; the species of Achnanthidium, Cocconeis, Cyclostephanos, Cyclotella, Gomphonema, Lemnicola, Navicula, Nitzschia, and Stephanodiscus genera were the most common. The wide distribution of small centric planktonic taxa, Cyclostephanos dubius, C. invisitatus, Cyclotella pseudostelligera, Stephanodiscus hantzschii, and S. minutulus, is preconditioned by the depletion of dissolved silica, which is a result of the high phosphorus load. The high abundance of macrophytes in the shallowest sites favors the dominance of epiphytic Fragilaria, Staurosira, and Staurosirella taxa. Bottom-living diatoms in the shallow eutrophic and hypereutrophic urban ponds are light-limited; this is a result of either macrophytes or phytoplankton development. Alkaliphilous and alkalibiontic species prevail among the pH-indicative species, while eutraphentic and hypereutraphentic diatoms, as well as those thriving in a wide range of trophic conditions, dominate over other trophic groups. The β- and α-mesosaprobic species are the most common saprobity-indicative taxa.  相似文献   

9.
Twenty-two sites were monitored in the Lower Sassandra River Basin (Côte d’Ivoire, West Africa) to examine patterns in fish species assemblage structure along environmental gradients. Hierarchical clustering of the species presence–absence data identified four types of assemblages corresponding to the man-made Lake Buyo, the main channel, and the two major tributaries. Canonical Correspondence Analysis (CCA) indicated that canopy closure, leaves-wood, aquatic plants, temperature, width, total dissolved solids and depth were the environmental factors most strongly correlated with variation in the fish assemblages. Five species: Papyrocranus afer, Micralestes elongatus, Parailia pellucida, Tilapia busumana and T. mariae were reported from the basin for the first time. The investigation of the variation in species richness led to the assessment of a major anthropogenic disturbance induced by a palm oil factory. In conjunction with the fact that the Sassandra River hosts an endemic species, Synodontis koensis, it was concluded that this basin is of high conservation priority.  相似文献   

10.
Based on the data collected from the Suichuan and Shushui Rivers, both tributaries of the Ganjiang River between April and July of 2015, the fish species identified were classified into 68 and 46 species, 14 and 12 families in the Suichuan River and Shushui River respectively. Cyprinidae is the most common family that accounts for 52.9% and 58.7% in the total number of fish species in the Suichuan River and Shushui River, respectively. The dominant species were Pseudohemiculter dispar, Squalidus argentatus, Silurus asotus and Leptobotia elongate for the Suichuan River and Squalidus argentatus, Acrossocheilus parallens, Pseudohemiculter dispar, Silurus asotus, Pelteobagrus fulvidraco, Acrossocheilus fasciatus and Zacco platypus for the Shushui River. The diversity of fish species showed more abundant and diverse for the Suichuan River. The composition of ecotype of fish indicated the rich diversities of ecotype in both the Suichuan and Shushui Rivers. The tributary (Suichuan River) and main stream of the Ganjiang River demonstrated a highly fauna similarity and the fish resources indicated its significance to maintain the fish diversity in the middle of the Ganjiang River and its benefits to the existence of the fish species in mountain streams. Dam construction, sand excavation and heavy metal pollution are the most significant threat to fish diversity and ecosystem functioning in Ganjiang River basin. In order to protect fish diversity and fisheries more effectively, relevant laws should be strengthened and conservation areas should be established for the survival of freshwater fish species.  相似文献   

11.
Management of semi-natural grasslands should be based on the requirements of plants as well as their pollinators since conditions beneficial for plants are not necessarily beneficial for their pollinators and vice versa. The factors affecting the reproductive success (fruit set) of Platanthera bifolia and Platanthera chlorantha and their pollinators in agricultural landscape and woodlands were studied. In the years 2014–2016, we observed and caught moths during the flowering period of Platanthera species (late June–mid July) in four pure P. bifolia, five pure P. chlorantha and nine mixed populations under management or no management in Estonia. We determined pollinator species richness, pollinator abundance, fruit set and visibility of Platanthera plants in each population. We found that pollinator assemblages of P. bifolia and P. chlorantha did not differ between managed and unmanaged sites. Pollinator abundance had an effect on the fruit set of P. bifolia but not on that of P. chlorantha. Presence or absence of management, visibility of plants and rarefied pollinator species richness did not affect the fruit set of either plant species. Pollinator abundance was significantly higher in unmanaged populations of both plant species but rarefied pollinator species richness was higher only in unmanaged populations of P. chlorantha. Based on our findings the recommendations for management of semi-natural grasslands are to promote larger landscape diversity for the benefit of moth abundance by leaving unmanaged patches in different parts of a grassland in different years and rotational and post-fruiting management for higher reproductive success of orchids.  相似文献   

12.
Human mediated introductions of non-indigenous crayfish species (NICS) are responsible for their rapid colonisation of European freshwaters. The introduction of North American crayfish is furthermore linked to the spread of crayfish plague and the decline of indigenous crayfish species (ICS). As the management of ICS and NICS have become necessary, a detailed knowledge on their distribution and ecological requirements is needed. We studied the current range of native noble crayfish Astacus astacus and stone crayfish Austropotamobius torrentium, as well as alien signal crayfish Pacifastacus leniusculus in Carinthia (Austria) and evaluated environmental and physical habitat features in streams with and without crayfish. Meanwhile, the loss of many ICS populations was recorded and alien P. leniusculus was found to be widespread in this region. Most of the habitat features of streams having crayfish differed significantly from sites lacking crayfish for at least one investigated native or alien species. Furthermore, multivariate and regression analyses showed specific differences in the habitat use of the investigated crayfish. Our results showed that the presence of alien P. leniusculus was associated with larger and smoother sloped lowland rivers, while the occurrence of the two native species was confined to smaller streams either at higher altitudes and with distinct physical habitat conditions (A. torrentium) or with moderate water temperatures (A. astacus). This study helps to identify potential refuge areas for the endangered native species and to predict the further spread of the most common non-native crayfish species in European streams.  相似文献   

13.
Agarum clathratum, brown algae, play important ecological roles in marine ecosystem, but can cause secondary environment pollution when they pile up on the beach. In order to resolve the environment problem by A. clathratum, we focus to isolate and identify Penicillium because many species are well known to produce extracellular enzymes. A total of 32 Penicillium strains were isolated from A. clathratum samples that collected from 13 sites along the mid-east coast of Korea in summer. They were identified based on morphological characters and phylogenetic analysis using β-tubulin DNA sequences as well as a combined dataset of β-tubulin and calmodulin. A total of 32 strains were isolated and they were identified to 13 Penicillium species. The commonly isolated species were Penicillium citrinum, P. roseomaculatum, and Penicillium sp. Among 13 Penicillium species, four species – P. bilaiae, P. cremeogriseum, P. madriti, and P. roseomaculatum – have not been previously recorded in Korea. For these four new species records to Korea, we provide morphological characteristics of each strain.  相似文献   

14.
Kelp forests dominate temperate and polar rocky coastlines and represent critical marine habitats because they support elevated rates of primary and secondary production and high biodiversity. A major threat to the stability of these ecosystems is the proliferation of non-native species, such as the Japanese kelp Undaria pinnatifida (‘Wakame’), which has recently colonised natural habitats in the UK. We quantified the abundance and biomass of U. pinnatifida on a natural rocky reef habitat over 10 months to make comparisons with three native canopy-forming brown algae (Laminaria ochroleuca, Saccharina latissima, and Saccorhiza polyschides). We also examined the biogenic habitat structure provided by, and epibiotic assemblages associated with, U. pinnatifida in comparison to native macroalgae. Surveys conducted within the Plymouth Sound Special Area of Conservation indicated that U. pinnatifida is now a dominant and conspicuous member of kelp-dominated communities on natural substrata. Crucially, U. pinnatifida supported a structurally dissimilar and less diverse epibiotic assemblage than the native perennial kelp species. However, U. pinnatifida-associated assemblages were similar to those associated with Saccorhiza polyschides, which has a similar life history and growth strategy. Our results suggest that a shift towards U. pinnatifida dominated reefs could result in impoverished epibiotic assemblages and lower local biodiversity, although this could be offset, to some extent, by the climate-driven proliferation of L. ochroleuca at the poleward range edge, which provides complex biogenic habitat and harbours relatively high biodiversity. Clearly, greater understanding of the long-term dynamics and competitive interactions between these habitat-forming species is needed to accurately predict future biodiversity patterns.  相似文献   

15.
The study of phytoplankton in lakes, sors, streams, and rivers of the Yarayakha River basin with the help of scanning electron microscopy has made it possible to broaden the taxonomic spectrum of Bacillariophyta; 236 specific and intraspecific taxa from 63 genera are detected. A total of 16 species and varieties that are new for the flora of Russia were documented; 30 forms from 18 genera are identified only to the species. The maximum species diversity is recorded in a stream in the Yarayakha River mouth (82 species) and in the channel of the Khureikhotarka River (105 species). Species such as Cyclotella meneghiniana, Fragilaria exiguiformis, Navicula hanseatica, Neidium bisulcatum, Stauroneis anceps, Thalassiosira inserta, and Tabellaria flocculosa are the most widespread in the waterbodies.  相似文献   

16.
17.
Bleaching response of coral species in the context of assemblage response   总被引:1,自引:0,他引:1  
Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon-α and -β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly sensitive to weak stress (α > 0) but under-responsive compared to assemblage bleaching (β < 1), or a threshold response, insensitive to weak stress (α < 0) but over-responsive compared to assemblage bleaching (β > 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation.  相似文献   

18.
Predaceous ladybirds are important natural enemies of many insect pests in terrestrial ecosystems such as peatlands, which are habitats for specialized cold-adapted plants. Ladybird assemblages of pristine peat bogs have not yet been assessed. In total, 15 ladybird species were recorded in peat bog in Belarus by using entomological sweep net. The present study shows low diversity, evenness and species richness of ladybird assemblages. However, a small number of species were present in high numbers. These are Coccinella hieroglyphica, Chilocorus bipustulatus, Coccinulla qutuordecimpustulata and Hippodamia tredecimpunctata. Ladybird abundance was positively related to shrub cover and number of vascular plant species, and negatively related to herb cover. In terms of ladybird diversity, only shrub cover had a significant negative effect.  相似文献   

19.
Lower Callovian deposits (subpatruus and koenigi ammonite zones) in the Mikhailovskii Mine section (Central Russia, Kursk Region) yielded 13 ostracode species (two of them are new) belonging to ten genera. This ostracode assemblage corresponds to ostracode beds with Praeschuleridea wartae-Pleurocythere kurskensis. The stratigraphic range of these beds corresponds to three ammonite biohorizons: Chamoussetia crobyloides, Kepplerites gowerianus gowerianus, and K. indigestus. Three distinct ostracode assemblages have been defined in the section based on their taxonomy and occurrence pattern. Two new species, Pleurocythere kurskensis sp. nov. and Pseudohutsonia wienholzae sp. nov., are described.  相似文献   

20.
We use public records from 1980 to 2014 to analyse survival of the EU Annex IV species Aeshna viridis in Sweden, a dragonfly strongly associated with the plant Stratiotes aloides. We clustered localities with S. aloides based on assumed dispersal abilities of A. viridis, using a dispersing radius of 2–100 km, calculating the proportion of sites with S. aloides that A. viridis is able to reach. If mean dispersal capability is high (40 km or above) 92.6 % or more of the localities are connected. For a good disperser, the probability of long-time survival is good. We further analysed the species richness of other Odonata and aquatic plants at 98 localities from the dataset. A. viridis co-occurred with more Odonata in the presence of S. aloides and running water but not in lakes. S. aloides sites had a higher number of other aquatic plants. Area had no impact on the occurrence of the species. For the present situation we surveyed 32 localities with known occurrence of the species. Only half of the sites for S. aloides contained any specimens while A. viridis occurred in the same number of sites. The species co-occurred in only 8 of 32 sites. In four sites A. viridis larvae appeared among Menyanthes trifoliata, Phragmites australis, Potamogeton natans and Sphagnum spp., indicating that at high latitudes A. viridis breeds among other species. Indirect monitoring based only on S. aloides would underestimate the number of populations of the dragonfly.  相似文献   

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